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''Panoplosaurus'' was originally named simply as a genus of armoured dinosaur by Lambe in 1919, within the group [[Stegosauria]],<ref name="lambe1919"/> though it was subsequently specified by Sternberg in 1921 that within Stegosauria it was closest to taxa like ''[[Ankylosaurus]]'' and ''[[Euoplocephalus]]'', and so within [[Ankylosauridae]].<ref name="sternberg1921"/> The description of the new genus ''Edmontonia'' in [[1928 in paleontology|1928]] by Sternberg identified it as a very close relative of ''Panoplosaurus'', almost close enough to be considered the same genus, both being closely related to ''[[Palaeoscincus]]''.<ref name="sternberg1928">{{cite journal|last=Sternberg|first=C.M.|year=1928|title=A new armored dinosaur from the Edmonton Formation of Alberta|journal=Transactions of the Royal Society of Canada|volume=22|issue=4|pages=93-106}}</ref> Following further description of the armoured taxon ''[[Struthiosaurus]]'' by [[Franz Nopcsa]] in [[1929 in paleontology|1929]], a different classification war proposed. [[Thyreophora]] replaced Stegosauria as the clade encompassing multiple families, with ''Panoplosaurus'' falling alongside ''Edmontonia'', ''[[Dyoplosaurus]]'', ''[[Hierosaurus]]'', ''[[Scolosaurus]]'' and ''[[Stegopelta]]'' within the new subfamily [[Panoplosaurinae]], which formed the family [[Nodosauridae]] with [[Nodosaurinae]], [[Ankylosaurinae]] and [[Acanthopholinae]].<ref name="nopcsa1929">{{cite journal|last=Nopcsa|first=F.|year=1929|title=Dinosaurierreste aus Siebenbürgen V|journal=Geologica Hungarica, series palaeontologica|volume=4|pages=1-76}}</ref> Nopcsa's classification of Panoplosaurinae was ammended slightly by [[Charles W. Gilmore]] in [[1930 in paleontology|1930]], who moved ''Palaeoscincus'' into the subfamily and removed ''Dyoplosaurus'', which was discovered to have the skull of an ankylosaurine.<ref name="gilmore1930">{{cite journal|last=Gilmore|first=C.W.|year=1930|title=On dinosaurian reptiles from the Two Medicine Formation of Montana|journal=Proceedings of the United States National Museum|volume=77|issue=2839|pages=1-38}}</ref> ''Panoplosaurus'' was then placed in the new subfamily [[Edmontoniinae]] by Loris S. Russell in [[1940 in paleontology|1940]], along with ''Edmontonia'' and ''Palaeoscincus'',<ref name="russell1940">{{cite journal|last=Russell|first=L.S.|year=1940|title=''Edmontonia rugosidens'' (Gilmore), an armoured dinosaur from the Belly River Series of Alberta|journal=university of Toronto Studies, Geological Series|volume=43|pages=3-27}}</ref> an equivalent classification to Gilmore's where Panoplosaurinae was used.<ref name="coombs1971">{{cite journal|last=Coombs|first=W.P.|year=1971|title=The Ankylosauria|journal=Ph.D. Dissertation, Columbia University|volume=72|issue=1291|pages=1-487}}</ref> Disagreeing with the classifications based on the work of Nopcsa, [[Evgeny Maleev]] moved ''Panoplosaurus'' into the family Ankylosauridae, which he considered to contain all ankylosaurs except ''[[Syrmosaurus]]''.<ref name="maleev1956">{{cite journal|last=Maleev|first=E.A.|year=1956|title=Pantsyrnye dinosavry verchnego mela Mongolii (Semeustvo Ankylosauridae)|journal=Trudy Paleontologicheskogo Instituta Akademiy Nauk SSSR|volume=62|pages=51-91}}</ref>
''Panoplosaurus'' was originally named simply as a genus of armoured dinosaur by Lambe in 1919, within the group [[Stegosauria]],<ref name="lambe1919"/> though it was subsequently specified by Sternberg in 1921 that within Stegosauria it was closest to taxa like ''[[Ankylosaurus]]'' and ''[[Euoplocephalus]]'', and so within [[Ankylosauridae]].<ref name="sternberg1921"/> The description of the new genus ''Edmontonia'' in [[1928 in paleontology|1928]] by Sternberg identified it as a very close relative of ''Panoplosaurus'', almost close enough to be considered the same genus, both being closely related to ''[[Palaeoscincus]]''.<ref name="sternberg1928">{{cite journal|last=Sternberg|first=C.M.|year=1928|title=A new armored dinosaur from the Edmonton Formation of Alberta|journal=Transactions of the Royal Society of Canada|volume=22|issue=4|pages=93-106}}</ref> Following further description of the armoured taxon ''[[Struthiosaurus]]'' by [[Franz Nopcsa]] in [[1929 in paleontology|1929]], a different classification war proposed. [[Thyreophora]] replaced Stegosauria as the clade encompassing multiple families, with ''Panoplosaurus'' falling alongside ''Edmontonia'', ''[[Dyoplosaurus]]'', ''[[Hierosaurus]]'', ''[[Scolosaurus]]'' and ''[[Stegopelta]]'' within the new subfamily [[Panoplosaurinae]], which formed the family [[Nodosauridae]] with [[Nodosaurinae]], [[Ankylosaurinae]] and [[Acanthopholinae]].<ref name="nopcsa1929">{{cite journal|last=Nopcsa|first=F.|year=1929|title=Dinosaurierreste aus Siebenbürgen V|journal=Geologica Hungarica, series palaeontologica|volume=4|pages=1-76}}</ref> Nopcsa's classification of Panoplosaurinae was ammended slightly by [[Charles W. Gilmore]] in [[1930 in paleontology|1930]], who moved ''Palaeoscincus'' into the subfamily and removed ''Dyoplosaurus'', which was discovered to have the skull of an ankylosaurine.<ref name="gilmore1930">{{cite journal|last=Gilmore|first=C.W.|year=1930|title=On dinosaurian reptiles from the Two Medicine Formation of Montana|journal=Proceedings of the United States National Museum|volume=77|issue=2839|pages=1-38}}</ref> ''Panoplosaurus'' was then placed in the new subfamily [[Edmontoniinae]] by Loris S. Russell in [[1940 in paleontology|1940]], along with ''Edmontonia'' and ''Palaeoscincus'',<ref name="russell1940">{{cite journal|last=Russell|first=L.S.|year=1940|title=''Edmontonia rugosidens'' (Gilmore), an armoured dinosaur from the Belly River Series of Alberta|journal=university of Toronto Studies, Geological Series|volume=43|pages=3-27}}</ref> an equivalent classification to Gilmore's where Panoplosaurinae was used.<ref name="coombs1971">{{cite journal|last=Coombs|first=W.P.|year=1971|title=The Ankylosauria|journal=Ph.D. Dissertation, Columbia University|volume=72|issue=1291|pages=1-487}}</ref> Disagreeing with the classifications based on the work of Nopcsa, [[Evgeny Maleev]] moved ''Panoplosaurus'' into the family Ankylosauridae, which he considered to contain all ankylosaurs except ''[[Syrmosaurus]]''.<ref name="maleev1956">{{cite journal|last=Maleev|first=E.A.|year=1956|title=Pantsyrnye dinosavry verchnego mela Mongolii (Semeustvo Ankylosauridae)|journal=Trudy Paleontologicheskogo Instituta Akademiy Nauk SSSR|volume=62|pages=51-91}}</ref>
[[File:Edmontonia Royal Tyrrell 1.jpg|thumb|left|Skull of ''Edmontonia rugosidens'' in the [[Royal Tyrrell Museum of Paleontology|RTMP]], at times considered a species of ''Panoplosaurus'']]
[[File:Edmontonia Royal Tyrrell 1.jpg|thumb|left|Skull of ''Edmontonia rugosidens'' in the [[Royal Tyrrell Museum of Paleontology|RTMP]], at times considered a species of ''Panoplosaurus'']]
Coombs reviewed and revised the classifications of Ankylosauria in 1978, which he used as the group to encompass all heavily armoured ornithischians in a similar usage to Nodosauridae of Nopcsa.<ref name="coombs1978"/><ref name="coombs1971"/> Within this suborder, he divided all taxa into two families, Ankylosauridae and Nodosauridae, distinguished by cranial and postcranial anatomy. Within Nodosauridae, which he considered a senior synonym of Acanthopholinae, Panoplosaurinae, Edmontoniinae, and other equivalent names, Coombs synonymized ''Panoplosaurus'' with ''Edmontonia'', making ''Panoplosaurus'' the only Late Cretaceous nodosaurid from North America.<ref name="coombs1978"/> Panoplosaurinae was then revived in [[1986 in paleontology|1986]] by [[Paul Sereno]], who used it to unite ''Panoplosaurus'', ''[[Sauropelta]]'', ''[[Silvisaurus]]'' and ''[[Struthiosaurus]]'' within Nodosauridae, excluding ''[[Hylaeosaurus]]'' and ''[[Polacanthus]]''.<ref name="sereno1986">{{cite journal|last=Sereno|first=P.C.|year=1986|title=Phylogeny of the bird-hipped dinosaurs|journal=National Geographic Research|volume=2|pages=234-256}}</ref> [[Robert Bakker]] then redescribed specimens from the Late Cretaceous of North America in [[1988 in paleontology|1988]], prompting him to separate ''Edmontonia rugosidens'' into the new subgenus ''[[Chassternbergia]]'', remove a specimen from ''Edmontonia longiceps'' making it the new genus ''[[Denversaurus]]'', and identify a former specimen of ''Panoplosaurus mirus'' as ''P.'' sp.. To distinguish the ''Panoplosaurus'' species from the ''Edmontonia'' complex, Bakker placed ''Panoplosaurus'' in Panoplosaurinae, and ''Edmontonia'', ''Chassternbergia'' and ''Denversaurus'' in Edmontoniinae, uniting the two subfamilies into the family [[Edmontoniidae]], which he placed in [[Nodosauroidea]], the family Nodosauridae of Coombs elevated to superfamily rank.<ref name="bakker1988">{{cite journal|last=Bakker|first=R.T.|year=1988|title=Review of the Late Cretaceous nodosauroid Dinosauria: ''Denversaurus schlessmani'', a new armor-plated dinosaur from the Latest Cretaceous of South Dakota, the last survivor of the nodosaurians, with comments on Stegosaur-Nodosaur relationships|journal=Hunteria|volume=1|issue=3|pages=1-23}}</ref> Carpenter further reviewed Late Cretaceous North American nodosaurids in 1990, concluding that Bakker's justification for separation was lacking, placing ''Chassternbergia'' and ''Denversaurus'' as junior synonyms of ''Edmontonia'', and only narrowing down the classification of ''Panoplosaurus'' and ''Edmontonia'' to Nodosauridae.<ref name="carpenter1990"/> In [[1998 in paleontology|1998]], Sereno modified his earlier position, using the name Nodosaurinae for the group of derived nodosaurids including ''Panoplosaurus'', and informally defining the subfamily as all taxa closer to ''Panoplosaurus'' than ''[[Sarcolestes]]'' or ''Hylaeosaurus''.<ref name="sereno1998">{{cite journal|last=Sereno|first=P.C.|year=1998|title=A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria|journal=Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen|volume=210|issue=8|pages=41-83}}</ref> Tracy Ford published a novel classification of ''Panoplosaurus'' in [[2000 in paleontology|2000]], using osteoderm anatomy to divide Nodosauridae into Nodosaurinae including only ''[[Nodosaurus]]'', [[Sauropeltinae]] including ''Sauropelta'' and ''Silvisaurus'', Edmontoniinae including ''Edmontonia'' and a distinct ''Chassternbergia'', and Panoplosaurinae including only ''Panoplosaurus''.<ref name="ford2000">{{cite journal|last=Ford|first=T.|year=2000|title=A review of ankylosaur osteoderms from New Mexico and a preliminary review of ankylosaur armor|editor-last=Lucas|editor-first=S.G.|editor2-last=Heckert|editor2-first=A.B.|journal=New Mexico Museum of Natural History and Science Bulletin|volume=17|pages=157-176}}</ref>
Coombs reviewed and revised the classifications of Ankylosauria in 1978, which he used as the group to encompass all heavily armoured ornithischians in a similar usage to Nodosauridae of Nopcsa.<ref name="coombs1978"/><ref name="coombs1971"/> Within this suborder, he divided all taxa into two families, Ankylosauridae and Nodosauridae, distinguished by cranial and postcranial anatomy. Within Nodosauridae, which he considered a senior synonym of Acanthopholinae, Panoplosaurinae, Edmontoniinae, and other equivalent names, Coombs synonymized ''Panoplosaurus'' with ''Edmontonia'', making ''Panoplosaurus'' the only Late Cretaceous nodosaurid from North America.<ref name="coombs1978"/> Panoplosaurinae was then revived in [[1986 in paleontology|1986]] by [[Paul Sereno]], who used it to unite ''Panoplosaurus'', ''[[Sauropelta]]'', ''[[Silvisaurus]]'' and ''[[Struthiosaurus]]'' within Nodosauridae, excluding ''[[Hylaeosaurus]]'' and ''[[Polacanthus]]''.<ref name="sereno1986">{{cite journal|last=Sereno|first=P.C.|year=1986|title=Phylogeny of the bird-hipped dinosaurs|journal=National Geographic Research|volume=2|pages=234-256}}</ref> [[Robert Bakker]] then redescribed specimens from the Late Cretaceous of North America in [[1988 in paleontology|1988]], prompting him to separate ''Edmontonia rugosidens'' into the new subgenus ''[[Chassternbergia]]'', remove a specimen from ''Edmontonia longiceps'' making it the new genus ''[[Denversaurus]]'', and identify a former specimen of ''Panoplosaurus mirus'' as ''P.'' sp.. To distinguish the ''Panoplosaurus'' species from the ''Edmontonia'' complex, Bakker placed ''Panoplosaurus'' in Panoplosaurinae, and ''Edmontonia'', ''Chassternbergia'' and ''Denversaurus'' in Edmontoniinae, uniting the two subfamilies into the family [[Edmontoniidae]], which he placed in [[Nodosauroidea]], the family Nodosauridae of Coombs elevated to superfamily rank.<ref name="bakker1988">{{cite journal|last=Bakker|first=R.T.|year=1988|title=Review of the Late Cretaceous nodosauroid Dinosauria: ''Denversaurus schlessmani'', a new armor-plated dinosaur from the Latest Cretaceous of South Dakota, the last survivor of the nodosaurians, with comments on Stegosaur-Nodosaur relationships|journal=Hunteria|volume=1|issue=3|pages=1-23}}</ref> Carpenter further reviewed Late Cretaceous North American nodosaurids in 1990, concluding that Bakker's justification for separation was lacking, placing ''Chassternbergia'' and ''Denversaurus'' as junior synonyms of ''Edmontonia'', and only narrowing down the classification of ''Panoplosaurus'' and ''Edmontonia'' to Nodosauridae.<ref name="carpenter1990"/> In [[1998 in paleontology|1998]], Sereno modified his earlier position, using the name Nodosaurinae for the group of derived nodosaurids including ''Panoplosaurus'', and informally defining the subfamily as all taxa closer to ''Panoplosaurus'' than ''[[Sarcolestes]]'' or ''Hylaeosaurus''.<ref name="sereno1998">{{cite journal|last=Sereno|first=P.C.|year=1998|title=A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria|journal=Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen|volume=210|issue=8|pages=41-83}}</ref> Tracy Ford published a novel classification of ''Panoplosaurus'' in [[2000 in paleontology|2000]], using osteoderm anatomy to divide Nodosauridae into Nodosaurinae including only ''[[Nodosaurus]]'', [[Sauropeltinae]] including ''Sauropelta'' and ''Silvisaurus'', Edmontoniinae including ''Edmontonia'' and a distinct ''Chassternbergia'', and Panoplosaurinae including only ''Panoplosaurus''.<ref name="ford2000">{{cite book|last=Ford|first=T.|year=2000|chapter=A review of ankylosaur osteoderms from New Mexico and a preliminary review of ankylosaur armor|editor-last=Lucas|editor-first=S.G.|editor2-last=Heckert|editor2-first=A.B.|title=Dinosaurs of New Mexico|journal=New Mexico Museum of Natural History and Science Bulletin|volume=17|pages=157-176}}</ref>

The first phylogenetic analysis to include ''Panoplosaurus'' was that of Yuong-Nam Lee in [[1996 in paleontology|1996]],<ref name="thompson2012">{{cite journal|last=Thompson|first=R.S.|last2=Parish|first2=J.C.|last3=Maidment|first3=S.C.R.|last4=Barrett|first4=P.M.|year=2012|title=Phylogeny of the ankylosaurian dinosaurs (Ornithischia: Thyreophora)|journal=Journal of Systematic Palaeontology|volume=10|issue=2|pages=301–312|doi=10.1080/14772019.2011.569091}}</ref> where ''Panoplosaurus mirus'', including both CMN 2759 and ROM 1215 nested next to ''Edmontonia'', which included both ''E. longiceps'' and ''E. rugosidens'', to the exclusion of all other nodosaurids.<ref name="lee1996">{{cite journal|last=Lee|first=Y.N.|year=1996|title=A new nodosaurid ankylosaur (Dinosauria: Ornithischia) from the Paw Paw Formation (Late Albian) of Texas|journal=Journal of Vertebrate Paleontology|volume=16|issue=2|pages=232–345|doi=10.1080/02724634.1996.10011311}}</ref> A similar union of ''Panoplosaurus'' and ''Edmontonia'' was recovered in [[1998 in paleontology|1998]] by Jim Kirkland and colleagues,<ref name="kirkland1998">{{cite book|last=Kirkland|first=J.I.|year=1998|chapter=A polacanthine ankylosaur (Ornithischia: Dinosauria) from the Early Cretaceous (Barremian) of eastern Utah|editor-last=Lucas|editor-first=S.G.|editor2-last=Kirkland|editor2-first=J.I.|editor3-last=Estep|editor3-first=J.W.|title=Lower and Middle Cretaceous Terrestrial Ecosystems|journal=New Mexico Museum of Natural History and Science Bulletin|volume=14|pages=271-281}}</ref> but the [[2001 in paleontology|2001]] analysis of Carpenter instead recovered ''Edmontonia'' closest to ''[[Animantarx]]'', while ''Panoplosaurus'' nested next to a clade of ''Sauropelta'' and ''Silvisaurus''.<ref name="carpenter2001">{{cite book|last=Carpenter|first=K.|year=2001|chapter=Phylogenetic analysis of the Ankylosauria|editor-last=Carpenter|editor-first=K.|title=The Armored Dinosaurs|publisher=Indiana University Press|pages=455-483|isbn=978-0-253-33964-5}}</ref> The [[2003 in paleontology|2003]] analysis of Robert Hill and colleagues resolved a group of ''Edmontonia'' and ''Animantarx'', with ''Panoplosaurus'' as the sister taxon,<ref name="hill2003">{{cite journal|last=Hill|first=R.V.|last2=Witmer|first2=L.W.|last3=Norell|first3=M.A.|year=2003|title=A New Specimen of ''Pinacosaurus grangeri'' (Dinosauria: Ornithischia) from the Late Cretaceous of Mongolia: Ontogeny and Phylogeny of Ankylosaurs|journal=American Museum Novitates|volume=3395|issue=3395|pages=1–29|doi=10.1206/0003-0082(2003)395<0001:ANSOPG>2.0.CO;2}}</ref> and the analysis of Matthew Vickaryous ''et al.'' recovered ''Panoplosaurus'' and ''Edmontonia'' as sisters,<ref name="vickaryous2004">{{cite book|last1=Vickaryous|first1=M.K.|last2=Maryanska|first2=T.|last3=Weishampel|first3=D.B.|year=2004|chapter=Ankylosauria|editor-last=Weishampel|editor-first=D.B.|editor2-last=Osmólska|editor2-first=H.|editor3-last=Dodson|editor3-first=P.|title=The Dinosauria|publisher=University of California Press|pages=363–392|isbn=9780520941434}}</ref> though ''Animantarx'' was not analysed.<ref name="thompson2012"/> Expansions on the analysis of Vickaryous and colleagues resolved the same clade of ''Panoplosaurus'' and ''Edmontonia'' with the additions of the nodosaurid ''[[Hungarosaurus]]'',<ref name="osi2005">{{cite journal|last=Ősi|first=A.|year=2005|title=''Hungarosaurus tormai'', a new ankylosaur (Dinosauria) from the Upper Cretaceous of Hungary|journal=Journal of Vertebrate Paleontology|volume=25|issue=2|pages=370–383|doi=10.1671/0272-4634(2005)025[0370:HTANAD]2.0.CO;2}}</ref> the ankylosaurid ''[[Crichtonsaurus benxiensis]]'',<ref name="lu2007">{{cite journal|last=Lü|first=J.|last2=Ji|first2=Q.|last3=Gao|first3=Y.|last4=Li|first4=Z.|year=2007|title=A New Species of the Ankylosaurid Dinosaur Crichtonsaurus (Ankylosauridae: Ankylosauria) from the Cretaceous of Liaoning Province, China|journal=Acta Geologica Sinica|volume=81|issue=6|pages=883–897|doi=10.1111/j.1755-6724.2007.tb01010.x}}</ref> the nodosaurid ''Struthiosaurus'',<ref name="osi2009">{{cite journal|last=Ősi|first=A.|last2=Makádi|first2=L.|year=2009|title=New remains of ''Hungarosaurus tormai'' (Ankylosauria, Dinosauria) from the Upper Cretaceous of Hungary: skeletal reconstruction and body mass estimation|journal=Paläontologische Zeitschrift|volume=83|pages=227-245|doi=10.1007/s12542-009-0017-5}}</ref> and the supposed ankylosaurus ''[[Tatankacephalus]]''.<ref name="parsons2009">{{cite journal|last=Parsons|first=W.L.|last2=Parsons|first2=K.M.|year=2009|title=A new ankylosaur (Dinosauria: Ankylosauria) from the Lower Cretaceous Cloverly Formation of central Montana|journal=Canadian Journal of Earth Sciences|volume=46|issue=10|pages=721-738|doi=10.1139/E09-045}}</ref> The next novel analysis was that of Richard Thompson and colleagues in [[2012 in paleontology|2012]], combining previous ankylosaurian analyses into a single one to analyse both Nodosauridae and Ankylosauridae. ''Panoplosaurus'' was resolved next to ''Edmontonia'', deep within an unresolved [[polytomy]] of all nodosaurids more derived than ''Animantarx'', which included ''[[Niobrarasaurus]]'', ''Nodosaurus'', ''Pawpawsaurus'', ''Sauropelta'', ''Silvisaurus'', ''[[Stegopelta]]'', and ''[[Texasetes]]''.<ref name="thompson2012"/> In [[2016 in paleontology|2016]], the phylogenetic analysis of Arbour and Currie initially meant to test the relationships of Ankylosauridae was expanded to include many of the nodosaurids known at the time, with ''Panoplosaurus'' limited to the holotype due to a lack of consensus about referred specimens.<ref name="arbour2016"/><ref name="arbour2016b">{{cite journal|last=Arbour|first=V.M.|last2=Zanno|first2=L.E.|last3=Gates|first3=T.|year=2016|title=Ankylosaurian dinosaur palaeoenvironmental associations were influenced by extirpation, sea-level fluctuation, and geodispersal|journal=Palaeogeography, Palaeoclimatology, Palaeoecology|volume=449|pages=289-299|doi=10.1016/j.palaeo.2016.02.033}}</ref> Following further modifications and expansions, ''Panoplosaurus'' was continually found within a group including ''Edmontonia'' and also at times ''Animantarx'', ''Texasetes'', ''Denversaurus'' (if considered separate from ''Edmontonia'') and an unnamed ankylosaur from [[Argentina]]. As a result of this consistent support, Daniel Madzia and colleagues decided to name the clade uniting all taxa closer to ''Panoplosaurus'' than ''Nodosaurus'' or ''Struthiosaurus'', giving it the formal name [[Panoplosaurini]], modifying the suffix ''-inae'' from previous uses as it was continually nested within the clade [[Nodosaurinae]].<ref name="madzia2021">{{cite journal|last=Madzia|first=D.|last2=Arbour|first2=V.M.|last3=Boyd|first3=C.A.|last4=Farke|first4=A.A.|last5=Cruzado-Caballero|first5=P.|last6=Evans|first6=D.C.|year=2021|title=The phylogenetic nomenclature of ornithischian dinosaurs|journal=PeerJ|volume=9|pages=e12362|doi=10.7717/peerj.12362}}</ref> The reference phylogeny for Panoplosaurini designated by Madzia and colleagues was that of Rivera-Sylva ''et al.'' ([[2018 in paleontology|2018]]),<ref name="madzia2021"/> which is a modified version of the Arbour and Currie analysis expanded to include the [[Mexico|Mexican]] taxon ''[[Acantholipan]]''. Their results can be seen below.<ref name="rivera2018">{{cite journal|last=Rivera-Sylva|first=H.E.|last2=Frey|first2=E.|last3=Stinnesbeck|first3=W.|last4=Carbot-Chanona|first4=G.|last5=Sanchez-Uribe|first5=I.E.|last6=Guzmán-Gutiérrez|first6=J.R.|year=2018|title=Paleodiversity of Late Cretaceous Ankylosauria from Mexico and their phylogenetic significance|journal=Swiss Journal of Palaeontology|volume=137|pages=83-93|doi=10.1007/s13358-018-0153-1}}</ref>
[[File:Dinosaur Exhibit at Houston Museum of Natural Science - Dec 2013.JPG|thumb|right|Mounted skeletons of ''[[Denversaurus]]'' and ''[[Tyrannosaurus]]'', [[Houston Museum of Natural Science]]]]
{{clade| style=font-size:85%; line-height:85%
|label1=[[Nodosaurinae]]
|1={{clade
|1=''[[Peloroplites]]''
|2={{clade
|1=''[[Taohelong]]''
|2=''[[Sauropelta]]''
|3={{clade
|1=''[[Acantholipan]]''
|2=''[[Nodosaurus]]''
|3={{clade
|1=''[[Niobrarasaurus]]''
|2=''[[Ahshislepelta]]'' }}
|4={{clade
|1=''[[Tatankacephalus]]''
|2={{clade
|1=''[[Silvisaurus]]''
|2={{clade
|1=CPC 273
|2={{clade
|1=[[Struthiosaurini]]
|label2=[[Panoplosaurini]]
|2={{clade
|1=''[[Animantarx]]''
|2={{clade
|1='''''Panoplosaurus'''''
|2={{clade
|1=Argentinian ankylosaur
|2=''[[Texasetes]]''
|3="''[[Denversaurus]]''"
|4=''[[Edmontonia longiceps]]''
|5=''[[Edmontonia rugosidens]]'' }} }} }} }} }} }} }} }} }} }} }}


==See also==
==See also==

Revision as of 06:41, 14 December 2021

Panoplosaurus
Temporal range: Campanian, 75.6 Ma
↓
Skull of holotype, CMN 2759
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: †Ornithischia
Clade: †Thyreophora
Clade: †Ankylosauria
Family: †Nodosauridae
Subfamily: †Nodosaurinae
Clade: †Panoplosaurini
Genus: †Panoplosaurus
Lambe, 1919[1]
Species:
†P. mirus
Binomial name
†Panoplosaurus mirus
Lambe, 1919[1]

Panoplosaurus (meaning "completely armoured lizard") is a genus of nodosaurid dinosaur. It was one of the last known nodosaurids, living during the Late Cretaceous in what is now North America; fossils have been located in Alberta, Canada.

Discovery

Outcrops of the Dinosaur Park Formation along the Red Deer River

In 1917, Canadian paleontologist Charles M. Sternberg of the Geological Survey of Canada discovered a complete skull and significant amount of the skeleton of an armoured dinosaur in the sandstone layers of Quarry 69 of the Belly River Group,[2] 64 m (210 ft) above sea level.[1] The specimen, designated by the Canadian Museum of Nature accession number CMN 2759, and excavated 4.43 km (2.75 mi) south of the mouth of the Little Sandhill tributary of the Red Deer River in Alberta, includes a nearly complete skull in articulation, most or all of the cervical vertebrae and the front dorsal vertebrae, and armour plates covering them, a majority of the disarticulated forelimb and three articulated fingers, a fragment of the pelvis and partial sacrum, a few bones of the foot, and multiple hundreds of osteoderms and dermal ossicles.[1] This material was being described by Canadian paleontologist Lawrence M. Lambe of the Geological Society, who completed the description of the skull and osteoderms prior to his death in March of 1919.[3] Lambe's work was published posthumously by the Royal Society of Canada, where he named the new material as Panoplosaurus mirus,[1] and a supplemental description of the vertebrae and limb material, which Lambe had not yet gotten to, was published by Sternberg in 1921.[3]

While the beds of discovery of the holotype, CMN 2759, were originally described as the Belly River beds,[1][3] they are now considered part of the upper level of the Dinosaur Park Formation, pertaining to the late middle Campanian, 75.6 million years ago.[4] Many additional specimens have since been referred to the genus, including Royal Ontario Museum (ROM) 1215 and Royal Tyrrell Museum of Paleontology (RTMP) 83.25.2 from the Dinosaur Park Formation of Alberta, and an unnumbered Oklahoma Museum of Natural History (OMNH) scapulocoracoid from the Aguja Formation of Texas.[2] A scapula from the Naashoibito member of the Kirtland Formation in New Mexico was referred to Panoplosaurus in 1981, but as it is from a different age and location from other specimens, may instead represent the ankylosaurid taxon Nodocephalosaurus, although this is uncertain due to lack of overlapping material.[5] 18 other specimens in the ROM, CMN, American Museum of Natural History, and Princeton University were referred to the genus by Walter P. Coombs in 1978, but these were referred on the assumption that Edmontonia was a synonym of Panoplosaurus,[6] which was considered unjustified by Kenneth Carpenter in a 1990 review on Late Cretaceous nodosaurids.[2] The referral of ROM 1215 to Panoplosaurus was questioned by Coombs in 1990,[7] and Roland A. Gangloff referred it and the Alaskan specimen DPMWA 90-25 to Edmontonia in 1995 based on the anatomy of the lack of diagnostic traits,[8] but Victoria Arbour and colleagues retained ROM 1215 in Panoplosaurus in 2009, limiting the genus to it, the holotype CMN 2759, and specimen AMNH 3072, all from the upper Dinosaur Park Formation.[4] Arbour and Philip J. Currie further restricted Panoplosaurus to just the holotype in 2016, as a result of uncertainties surrounding the referrals of various specimens between it, Edmontonia rugosidens and Edmontonia longiceps, all from the Dinosaur Park Formation and similar deposits.[9]

Description

Depiction of megaherbivores in the Dinosaur Park Formation, Panoplosaurus on the far right

Panoplosaurus was 5 to 7 metres (16 to 23 ft) long,[10][11] around 2 metres (6.6 ft) tall[citation needed], and had an estimated weight of 1.5–1.6 tonnes (1.7–1.8 short tons).[10][12] It was heavily armoured, even by the standards of other nodosaurs, probably with traverse bands of studded plates covering its back and tail, although the tail likely lacked the club found in ankylosaurids. Larger paired ovals of bony armour covered the neck, shoulders and front limbs. These ovals were keeled, possessing a prominent curved ridge on the outer surface. Spikes on the shoulder, that some other nodosaurids featured, were absent. The armour on the head was fused into a compact helmet-like shield; these plates had a lumpy surface. Also bony cheek scutes were present.[13]

The skull was short and wide at the back. The head of the holotype specimen is particularly rounded; the other two skulls are longer and flatter, perhaps reflecting age or gender differences. The animal had a relatively narrow snout, perhaps to aid in rooting about for low growing plants to eat and indicating a selective diet of highly nutritious food. Although the coracoid was slender and not fused to the scapula, the forelegs were particularly heavy, and had attachments for large muscles, which may suggest that the animal would have been surprisingly maneuverable in life, possibly being able to make defensive charges like a modern rhinoceros.[14] The hand perhaps had only three fingers. The pelvis was attached to four sacral vertebrae with short sacral ribs.

Classification

Panoplosaurus was originally named simply as a genus of armoured dinosaur by Lambe in 1919, within the group Stegosauria,[1] though it was subsequently specified by Sternberg in 1921 that within Stegosauria it was closest to taxa like Ankylosaurus and Euoplocephalus, and so within Ankylosauridae.[3] The description of the new genus Edmontonia in 1928 by Sternberg identified it as a very close relative of Panoplosaurus, almost close enough to be considered the same genus, both being closely related to Palaeoscincus.[15] Following further description of the armoured taxon Struthiosaurus by Franz Nopcsa in 1929, a different classification war proposed. Thyreophora replaced Stegosauria as the clade encompassing multiple families, with Panoplosaurus falling alongside Edmontonia, Dyoplosaurus, Hierosaurus, Scolosaurus and Stegopelta within the new subfamily Panoplosaurinae, which formed the family Nodosauridae with Nodosaurinae, Ankylosaurinae and Acanthopholinae.[16] Nopcsa's classification of Panoplosaurinae was ammended slightly by Charles W. Gilmore in 1930, who moved Palaeoscincus into the subfamily and removed Dyoplosaurus, which was discovered to have the skull of an ankylosaurine.[17] Panoplosaurus was then placed in the new subfamily Edmontoniinae by Loris S. Russell in 1940, along with Edmontonia and Palaeoscincus,[18] an equivalent classification to Gilmore's where Panoplosaurinae was used.[19] Disagreeing with the classifications based on the work of Nopcsa, Evgeny Maleev moved Panoplosaurus into the family Ankylosauridae, which he considered to contain all ankylosaurs except Syrmosaurus.[20]

Skull of Edmontonia rugosidens in the RTMP, at times considered a species of Panoplosaurus

Coombs reviewed and revised the classifications of Ankylosauria in 1978, which he used as the group to encompass all heavily armoured ornithischians in a similar usage to Nodosauridae of Nopcsa.[6][19] Within this suborder, he divided all taxa into two families, Ankylosauridae and Nodosauridae, distinguished by cranial and postcranial anatomy. Within Nodosauridae, which he considered a senior synonym of Acanthopholinae, Panoplosaurinae, Edmontoniinae, and other equivalent names, Coombs synonymized Panoplosaurus with Edmontonia, making Panoplosaurus the only Late Cretaceous nodosaurid from North America.[6] Panoplosaurinae was then revived in 1986 by Paul Sereno, who used it to unite Panoplosaurus, Sauropelta, Silvisaurus and Struthiosaurus within Nodosauridae, excluding Hylaeosaurus and Polacanthus.[21] Robert Bakker then redescribed specimens from the Late Cretaceous of North America in 1988, prompting him to separate Edmontonia rugosidens into the new subgenus Chassternbergia, remove a specimen from Edmontonia longiceps making it the new genus Denversaurus, and identify a former specimen of Panoplosaurus mirus as P. sp.. To distinguish the Panoplosaurus species from the Edmontonia complex, Bakker placed Panoplosaurus in Panoplosaurinae, and Edmontonia, Chassternbergia and Denversaurus in Edmontoniinae, uniting the two subfamilies into the family Edmontoniidae, which he placed in Nodosauroidea, the family Nodosauridae of Coombs elevated to superfamily rank.[22] Carpenter further reviewed Late Cretaceous North American nodosaurids in 1990, concluding that Bakker's justification for separation was lacking, placing Chassternbergia and Denversaurus as junior synonyms of Edmontonia, and only narrowing down the classification of Panoplosaurus and Edmontonia to Nodosauridae.[2] In 1998, Sereno modified his earlier position, using the name Nodosaurinae for the group of derived nodosaurids including Panoplosaurus, and informally defining the subfamily as all taxa closer to Panoplosaurus than Sarcolestes or Hylaeosaurus.[23] Tracy Ford published a novel classification of Panoplosaurus in 2000, using osteoderm anatomy to divide Nodosauridae into Nodosaurinae including only Nodosaurus, Sauropeltinae including Sauropelta and Silvisaurus, Edmontoniinae including Edmontonia and a distinct Chassternbergia, and Panoplosaurinae including only Panoplosaurus.[24]

The first phylogenetic analysis to include Panoplosaurus was that of Yuong-Nam Lee in 1996,[25] where Panoplosaurus mirus, including both CMN 2759 and ROM 1215 nested next to Edmontonia, which included both E. longiceps and E. rugosidens, to the exclusion of all other nodosaurids.[26] A similar union of Panoplosaurus and Edmontonia was recovered in 1998 by Jim Kirkland and colleagues,[27] but the 2001 analysis of Carpenter instead recovered Edmontonia closest to Animantarx, while Panoplosaurus nested next to a clade of Sauropelta and Silvisaurus.[28] The 2003 analysis of Robert Hill and colleagues resolved a group of Edmontonia and Animantarx, with Panoplosaurus as the sister taxon,[29] and the analysis of Matthew Vickaryous et al. recovered Panoplosaurus and Edmontonia as sisters,[30] though Animantarx was not analysed.[25] Expansions on the analysis of Vickaryous and colleagues resolved the same clade of Panoplosaurus and Edmontonia with the additions of the nodosaurid Hungarosaurus,[31] the ankylosaurid Crichtonsaurus benxiensis,[32] the nodosaurid Struthiosaurus,[33] and the supposed ankylosaurus Tatankacephalus.[34] The next novel analysis was that of Richard Thompson and colleagues in 2012, combining previous ankylosaurian analyses into a single one to analyse both Nodosauridae and Ankylosauridae. Panoplosaurus was resolved next to Edmontonia, deep within an unresolved polytomy of all nodosaurids more derived than Animantarx, which included Niobrarasaurus, Nodosaurus, Pawpawsaurus, Sauropelta, Silvisaurus, Stegopelta, and Texasetes.[25] In 2016, the phylogenetic analysis of Arbour and Currie initially meant to test the relationships of Ankylosauridae was expanded to include many of the nodosaurids known at the time, with Panoplosaurus limited to the holotype due to a lack of consensus about referred specimens.[9][35] Following further modifications and expansions, Panoplosaurus was continually found within a group including Edmontonia and also at times Animantarx, Texasetes, Denversaurus (if considered separate from Edmontonia) and an unnamed ankylosaur from Argentina. As a result of this consistent support, Daniel Madzia and colleagues decided to name the clade uniting all taxa closer to Panoplosaurus than Nodosaurus or Struthiosaurus, giving it the formal name Panoplosaurini, modifying the suffix -inae from previous uses as it was continually nested within the clade Nodosaurinae.[36] The reference phylogeny for Panoplosaurini designated by Madzia and colleagues was that of Rivera-Sylva et al. (2018),[36] which is a modified version of the Arbour and Currie analysis expanded to include the Mexican taxon Acantholipan. Their results can be seen below.[37]

Mounted skeletons of Denversaurus and Tyrannosaurus, Houston Museum of Natural Science
Nodosaurinae

See also

References

  1. ^ a b c d e f g Lambe, L.M. (1919). "Description of a new genus and species (Panoplosaurus mirus) of an armoured dinosaur from the Belly River Beds of Alberta". Transactions of the Royal Society of Canada. 3 (3): 39–50.
  2. ^ a b c d Carpenter, K. (1990). "Ankylosaur systematics: example using Panoplosaurus and Edmontonia (Ankylosauria: Nodosauridae)". In Carpenter, L.; Currie, P.J. (eds.). Dinosaur Systematics: Approaches and Perspectives. Cambridge University Press. pp. 281–298. ISBN 0-521-36672-0.
  3. ^ a b c d Sternberg, C.M. (1921). "A supplementary study of Panoplosaurus mirus". Transactions of the Royal Society of Canada. 4 (3): 93–102.
  4. ^ a b Arbour, V.M.; Burns, M.E.; Sissons, R.L. (2009). "A redescription of the ankylosaurid dinosaur Dyoplosaurus acutosquameus Parks, 1924 (Ornithischia: Ankylosauria) and a revision of the genus". Journal of Vertebrate Paleontology. 29 (4): 1117–1135. doi:10.1671/039.029.0405.
  5. ^ Sullivan, R. (1999). "Nodocephalosaurus kirtlandensis, gen et sp nov., a new ankylosaurid dinosaur (Ornithischia; Ankylosauria) from the Upper Cretaceous Kirtland Formation (Upper Campanian), San Juan Basin, New Mexico". Journal of Vertebrate Paleontology. 19 (1): 126–139. doi:10.1080/02724634.1999.10011128.
  6. ^ a b c Coombs, W.P. (1978). "The families of the ornithischian dinosaur order Ankylosauria". Palaeontology. 21 (1): 143–170.
  7. ^ Coombs, W.P. (1990). "Teeth and taxonomy in ankylosaurs". In Carpenter, L.; Currie, P.J. (eds.). Dinosaur Systematics: Approaches and Perspectives. Cambridge University Press. pp. 269–280. ISBN 0-521-36672-0.
  8. ^ Gangloff, R.A. (1995). "Edmontonia sp., the first record of an ankylosaur from Alaska". Journal of Vertebrate Paleontology. 15 (1): 195–200. doi:10.1080/02724634.1995.10011218.
  9. ^ a b Arbour, V.M.; Currie, P.J. (2016). "Systematics, phylogeny and palaeobiogeography of the ankylosaurid dinosaurs". Journal of Systematic Palaeontology. 14 (5): 385–444. doi:10.1080/14772019.2015.1059985.
  10. ^ a b Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 237
  11. ^ Holtz, Thomas R. Jr. (2011) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2010 Appendix.
  12. ^ Brown, C.M., Evans, D.C., Campione, N.E., O'Brien, L.J., Eberth, D.A. 2013. Evidence for Taphonomic Size Bias in the Dinosaur Park Formation (Campanian, Alberta), A Model Mesozoic Terrestrial Alluvial-Paralic System. Paleogeo. Paleoclim. Paleoeco. Vol. 372:108–122.
  13. ^ Carpenter, K. 1990. "Ankylosaur systematics: example using Panoplosaurus and Edmontonia (Ankylosauria: Nodosauridae):, In: Carpenter, K. & Currie, P. J. (eds) Dinosaur Systematics: Approaches and Perspectives. Cambridge University Press, Cambridge, pp. 281-298
  14. ^ Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 159. ISBN 1-84028-152-9.
  15. ^ Sternberg, C.M. (1928). "A new armored dinosaur from the Edmonton Formation of Alberta". Transactions of the Royal Society of Canada. 22 (4): 93–106.
  16. ^ Nopcsa, F. (1929). "Dinosaurierreste aus Siebenbürgen V". Geologica Hungarica, series palaeontologica. 4: 1–76.
  17. ^ Gilmore, C.W. (1930). "On dinosaurian reptiles from the Two Medicine Formation of Montana". Proceedings of the United States National Museum. 77 (2839): 1–38.
  18. ^ Russell, L.S. (1940). "Edmontonia rugosidens (Gilmore), an armoured dinosaur from the Belly River Series of Alberta". university of Toronto Studies, Geological Series. 43: 3–27.
  19. ^ a b Coombs, W.P. (1971). "The Ankylosauria". Ph.D. Dissertation, Columbia University. 72 (1291): 1–487.
  20. ^ Maleev, E.A. (1956). "Pantsyrnye dinosavry verchnego mela Mongolii (Semeustvo Ankylosauridae)". Trudy Paleontologicheskogo Instituta Akademiy Nauk SSSR. 62: 51–91.
  21. ^ Sereno, P.C. (1986). "Phylogeny of the bird-hipped dinosaurs". National Geographic Research. 2: 234–256.
  22. ^ Bakker, R.T. (1988). "Review of the Late Cretaceous nodosauroid Dinosauria: Denversaurus schlessmani, a new armor-plated dinosaur from the Latest Cretaceous of South Dakota, the last survivor of the nodosaurians, with comments on Stegosaur-Nodosaur relationships". Hunteria. 1 (3): 1–23.
  23. ^ Sereno, P.C. (1998). "A rationale for phylogenetic definitions, with application to the higher-level taxonomy of Dinosauria". Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen. 210 (8): 41–83.
  24. ^ Ford, T. (2000). "A review of ankylosaur osteoderms from New Mexico and a preliminary review of ankylosaur armor". In Lucas, S.G.; Heckert, A.B. (eds.). Dinosaurs of New Mexico. Vol. 17. pp. 157–176. {{cite book}}: |journal= ignored (help)
  25. ^ a b c Thompson, R.S.; Parish, J.C.; Maidment, S.C.R.; Barrett, P.M. (2012). "Phylogeny of the ankylosaurian dinosaurs (Ornithischia: Thyreophora)". Journal of Systematic Palaeontology. 10 (2): 301–312. doi:10.1080/14772019.2011.569091.
  26. ^ Lee, Y.N. (1996). "A new nodosaurid ankylosaur (Dinosauria: Ornithischia) from the Paw Paw Formation (Late Albian) of Texas". Journal of Vertebrate Paleontology. 16 (2): 232–345. doi:10.1080/02724634.1996.10011311.
  27. ^ Kirkland, J.I. (1998). "A polacanthine ankylosaur (Ornithischia: Dinosauria) from the Early Cretaceous (Barremian) of eastern Utah". In Lucas, S.G.; Kirkland, J.I.; Estep, J.W. (eds.). Lower and Middle Cretaceous Terrestrial Ecosystems. Vol. 14. pp. 271–281. {{cite book}}: |journal= ignored (help)
  28. ^ Carpenter, K. (2001). "Phylogenetic analysis of the Ankylosauria". In Carpenter, K. (ed.). The Armored Dinosaurs. Indiana University Press. pp. 455–483. ISBN 978-0-253-33964-5.
  29. ^ Hill, R.V.; Witmer, L.W.; Norell, M.A. (2003). "A New Specimen of Pinacosaurus grangeri (Dinosauria: Ornithischia) from the Late Cretaceous of Mongolia: Ontogeny and Phylogeny of Ankylosaurs". American Museum Novitates. 3395 (3395): 1–29. doi:10.1206/0003-0082(2003)395<0001:ANSOPG>2.0.CO;2.
  30. ^ Vickaryous, M.K.; Maryanska, T.; Weishampel, D.B. (2004). "Ankylosauria". In Weishampel, D.B.; Osmólska, H.; Dodson, P. (eds.). The Dinosauria. University of California Press. pp. 363–392. ISBN 9780520941434.
  31. ^ Ősi, A. (2005). "Hungarosaurus tormai, a new ankylosaur (Dinosauria) from the Upper Cretaceous of Hungary". Journal of Vertebrate Paleontology. 25 (2): 370–383. doi:10.1671/0272-4634(2005)025[0370:HTANAD]2.0.CO;2.
  32. ^ Lü, J.; Ji, Q.; Gao, Y.; Li, Z. (2007). "A New Species of the Ankylosaurid Dinosaur Crichtonsaurus (Ankylosauridae: Ankylosauria) from the Cretaceous of Liaoning Province, China". Acta Geologica Sinica. 81 (6): 883–897. doi:10.1111/j.1755-6724.2007.tb01010.x.
  33. ^ Ősi, A.; Makádi, L. (2009). "New remains of Hungarosaurus tormai (Ankylosauria, Dinosauria) from the Upper Cretaceous of Hungary: skeletal reconstruction and body mass estimation". Paläontologische Zeitschrift. 83: 227–245. doi:10.1007/s12542-009-0017-5.
  34. ^ Parsons, W.L.; Parsons, K.M. (2009). "A new ankylosaur (Dinosauria: Ankylosauria) from the Lower Cretaceous Cloverly Formation of central Montana". Canadian Journal of Earth Sciences. 46 (10): 721–738. doi:10.1139/E09-045.
  35. ^ Arbour, V.M.; Zanno, L.E.; Gates, T. (2016). "Ankylosaurian dinosaur palaeoenvironmental associations were influenced by extirpation, sea-level fluctuation, and geodispersal". Palaeogeography, Palaeoclimatology, Palaeoecology. 449: 289–299. doi:10.1016/j.palaeo.2016.02.033.
  36. ^ a b Madzia, D.; Arbour, V.M.; Boyd, C.A.; Farke, A.A.; Cruzado-Caballero, P.; Evans, D.C. (2021). "The phylogenetic nomenclature of ornithischian dinosaurs". PeerJ. 9: e12362. doi:10.7717/peerj.12362.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  37. ^ Rivera-Sylva, H.E.; Frey, E.; Stinnesbeck, W.; Carbot-Chanona, G.; Sanchez-Uribe, I.E.; Guzmán-Gutiérrez, J.R. (2018). "Paleodiversity of Late Cretaceous Ankylosauria from Mexico and their phylogenetic significance". Swiss Journal of Palaeontology. 137: 83–93. doi:10.1007/s13358-018-0153-1.

External links

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